The present invention generally relates to devices incorporating hemostasis valves. More specifically, the present invention relates to hemostasis valves for use with vascular introducer sheaths, catheters, Y-adapters and the like.
Vascular introducer sheaths are well known components of vascular access systems which are used in a wide variety of diagnostic and therapeutic vascular procedures, such as angiography, angioplasty and embolization procedures. Vascular access systems typically include an introducer sheath and a dilator. The introducer sheath usually includes a hemostasis valve which inhibits blood loss as guide wires, catheters and the like are introduced, passed through and manipulated in the sheath.
An example of a conventional vascular access system 10 is illustrated in FIG. 1. The vascular access system 10 includes two primary components, namely an introducer sheath 12 and a dilator 14. The introducer sheath 12 includes an elongate shaft 16 and a hemostasis valve assembly 18. A flush tube subassembly 20 may be connected to a side port 22 of the hemostasis assembly 18. Although not clearly visible, the hemostasis valve assembly 18 includes a hub, a cap and a gasket 30 (shown in FIGS. 2A and 2B) disposed therebetween.
The gasket 30 of the hemostasis valve assembly 18 forms a fluid seal about devices inserted therein to inhibit back-bleeding. The gasket 30 may comprise a disc of flexible polymeric material having a slit 32 extending therethrough as shown in FIG. 2A or a hole 34 as shown in FIG. 2B. The slit 32 is sufficiently flexible and the hole 34 is sufficiently sized to form a seal about devices inserted therein. The slit 32 is normally closed such that a hemostatic seal is formed with or without devices inserted therein. By contrast, the hole 34 is normally open such that a hemostatic seal is formed only with a device inserted therein.
An advantage of the slit 32 design is that back-bleeding is prevented at all timesxe2x80x94prior to, during and subsequent to device insertion. A disadvantage of the slit 32 design is that a significant amount of friction may be encountered when sliding devices therethrough. An advantage of the hole 34 design is that relatively little friction is encountered when sliding devices therethrough. A disadvantage of the hole 34 design is that back-bleeding may occur when no device is inserted therein (i.e., prior to and subsequent to device insertion). Accordingly, there is a need for a hemostasis valve which provides a fluid tight seal at all times to prevent back-bleeding, and offers relatively low friction when devices are inserted therein.
To address this need, the present invention provides an improved hemostasis valve for use with an intravascular device such as an introducer sheath, a catheter or the like. In all embodiments, the hemostasis valve may either be an integral part of the device, or releasable from the device as in a Y-adapter, a manifold or the like.
In one embodiment, the hemostasis valve is normally closed and is biased to a closed position in response to distal pressure to prevent back-bleeding. The hemostasis valve is also biased to an open position in response to proximal force or pressure to reduce friction when devices are inserted therein. For example, the hemostasis valve may comprise a plurality of flaps or leaflets, such as a bileaflet or trileaflet design. Preferably, the leaflets are cuspidate, such as a bicuspid or tricuspid design. Also preferably, the thickness of the leaflets is substantially less than the radial dimension thereof such that the leaflets readily deflect and conform. As an alternative, another hemostasis valve (e.g., a close-fit seal) may be utilized to ensure a fluid tight seal about devices inserted therein.
In another embodiment, the hemostasis valve is longitudinally actuated between an open position to reduce friction during device insertion and a closed position to prevent back-bleeding when no devices are inserted therein. The hemostasis valve may include a circular or helical pleat which changes in radial dimension upon longitudinal actuation. For example, the hemostasis valve may be bellows-shaped. The hemostasis valve may also include a radial compression member that toggles when the valve is closed to ensure a fluid tight seal.